#!/usr/bin/perl

use strict;
use warnings;

my $BUFSIZE  = 8;
my $data;

# read the data file
open(FH,"chargen") or die;
binmode(FH,":raw");
read(FH,$data,$BUFSIZE);     # $data contains 'ABCDEFGH'
close(FH);

print "Source:\n";
foreach (split //, $data) { to_binary($_); }
$data = transpose($data);
print "Destination:\n";
# --> cries foul in the sub for the next line
foreach (split //, $data) { to_binary($_); }

sub transpose {
    my $buf = shift;
    return if (length($buf) < $BUFSIZE);
    ($buf)  = substr($buf,0,$BUFSIZE) if (length($buf) > $BUFSIZE);
    my @in  = unpack("C*",$buf);     # get only ascii vals
    my @out = (0,0,0,0,0,0,0,0);
    my $newrow = 0;
    for my $row (reverse 0..($BUFSIZE-1)) { 
        for my $col (0..($BUFSIZE-1)) {
            $out[$newrow] |= (1 << $col)
                 if ($in[7 - $col] >> $row & 1);
        }
        $newrow++;
    }
    return pack("C*",@out);
}

sub to_binary {
    my $byte = shift;
    ($byte) = split //, $byte if (length($byte) > 1);
    for (reverse 0..($BUFSIZE-1)) {
        my $b = ord($byte); 
        print $b >> $_ & 1 ? "1" : "0";
    }
    print "\n";
}